Last week, Martin Dempsey, the Chairman of the Joint Chiefs of Staff, said that the U.S. would not be able to topple ISIS without striking the group in Syria. But over the weekend, U.S. officials said they did not yet have the intelligence needed to carry out such attacks. The approval of the surveillance flights is a seen as a step towards gathering it.

What will be the U.S.'s next military move against ISIS? We asked Steven Heydemann, vice president for applied research on conflict at Washington's U.S. Institute of Peace, to weigh in.

Syria Deeply: Hypothetically, what would U.S. strikes look like?

Steven Heydemann: I'm not so sure we're talking about hypotheticals. If you add up all of the recent statements from senior officials, it looks very much like we could see some sort of U.S. strike in a [very] short timeframe. I wouldn't want to predict precisely when I would expect this to occur, but I think we're talking about a matter of weeks and not months.

It seems to be that the pressures that are building on the administration to act are one significant pressure. In addition, we have this major ISIS offensive in the north of Syria, north of Aleppo, in which they are threatening the small city of Azaz, which has 50,000 inhabitants and is right on the Turkish border. It seems to me that with respect to the humanitarian threat and the threat to the security of Turkey - a NATO ally - and the need to blunt ISIS advances in Syria, the pieces are in place for a much faster decision to strike.

When and how that unfolds bumps up against a very difficult political balancing act that Obama has to tread. He has to act in a way that does not provide any opportunity to be seen as cooperating with the Assad regime. And it means acting in a way that avoids any possibility that a U.S. strike might generate political backlash that would be seen as too big a price to pay by the Obama administration. The most likely zone they would act in Syria would be the very far east, quite removed from populations, and with targets that would minimize both the potential for a Syrian regime response - which I would be surprised at in any event - and would also minimize the chance for any kind of civilian casualties, and would end up being far more symbolic than tactical.

If the administration wanted to do anything significant, they would use air power to blunt the ISIS offensive in Aleppo. But my own suspicion is that it's seen as politically too risky to do that.

Syria Deeply: Too risky as regards the American public? Or too risky with Assad?

Heydemann: I think it's partly an effort to avoid being seen as trapped in a process of mission creep in which the U.S. will become more deeply embroiled in another Middle East war, and a greater engagement than the American public views as appropriate. And I think that it's also to avoid the most blatant kind of challenges to the Assad regime's claims that any act would be a violation of sovereignty.

Even though Obama views the Assad regime as illegitimate, even though [White House advisor] Ben Rhodes has said that "the enemy of the enemy is not our friend," they are anxious to avoid being put in a position in which there is even a [remote] possibility they would encounter the regime's air force. One of the many nightmare scenarios out of all of this for the administration would be the downing of a U.S. [fighter] jet and the capture of a U.S. pilot.

So I think they have a very delicate balancing act to navigate, and ironically the only way they can walk through the political minefield is by acting in ways that are guaranteed to be ineffective.

Syria Deeply: Do you see any possible scenario unfolding where they do work with Assad?

Heydemann: Not now. I do think it is highly unlikely that either the U.S. or key Western governments would move in that direction now. We have to recognize what it would mean in terms of relationships with Gulf allies and Turkey. And what it means in terms of the possibility of any engagement with the moderate opposition.

One of the big political challenges for the administration is how to act in ways that cannot be portrayed as acting with the Syrian regime. Because if we take Obama seriously when he says: "Syrians should not be forced into a choice between dictatorship and terrorism," that means that we continue to view it as important to keep an alternative open. And if the U.S. were to be seen as working with the regime, that would be impossible.